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The Cameroon Mobile Phone SMS (CAMPS) trial: a randomized trial of text messaging versus usual care for adherence to antiretroviral therapy
Global Health Sciences Literature Digest
Published January 22, 2013
Journal Article

Mbuagbaw L, Thabane L, Ongolo-Zogo P, Lester RT, Mills EJ, Smieja M, Dolovich L, Kouanfack C. The Cameroon Mobile Phone SMS (CAMPS) trial: a randomized trial of text messaging versus usual care for adherence to antiretroviral therapy. PLoS One. 2012;7(12):e46909. doi: 10.1371/journal.pone.0046909. Epub 2012 Dec 6


To evaluate the use of weekly short messaging service (SMS) motivational mobile phone text messages for improving adherence to antiretroviral therapy (ART).


Yaoundé, Cameroon.

Study Design

Randomized controlled trial (RCT).


HIV-infected adults age ≥21 years.

Main Outcome Measures

The primary outcome was adherence. Secondary outcomes were all-cause mortality, change in CD4 count, change in viral load, change in body mass index, change in weight, opportunistic infections (OI), quality of life (QOL) and retention in the trial.


Participants were recruited from the Yaoundé Central Hospital Accredited Treatment Centre. Eligible subjects owned a mobile phone, could read text messages and had been on ART for at least one month. Patients were randomized to intervention and control arms with a 1:1 allocation ratio. A computer-generated randomization list was established by a statistician in Canada using random block sizes. The allocation codes were then sequentially affixed to the phone numbers of consecutively recruited participants by trained research staff. This sequence was sent to the research center by e-mail, and concealed in a password-protected computer until interventions were assigned. The research staff responsible for allocation had access to the allocation codes and the phone numbers of participants. The program secretary responsible for sending the text messages received the allocations ("SMS" or "No SMS") and corresponding phone numbers each week. The data analyst was also blinded to group allocation. Only the participants were aware of their allocation.

Investigators sent a once-weekly short text message to each participant in the SMS group, in either French or English, based on language preference. The content of the message was motivational, with a reminder component. The message also contained a phone number that recipients could call back if they needed help. The content was varied and contemporary (e.g. messages would contain holiday greetings) so as to retain participants' attention throughout the study period and to explore the various aspects of behavior change. An example of a message would be, "You are important to your family. Please remember to take your medication. You can call us at this number: +237 xxxx xxxx." The messages made no mention of HIV. Participants in the control group received no text messages.


Two hundred participants were randomized to either the SMS intervention arm (n=101) or the control arm (n=99). After randomization, both groups were fairly similar in baseline characteristics, though the median duration on ART was longer in the intervention arm. Participants in the SMS arm had been on ART for a median of 31 months (interquartile range [IQR] 15 months to 50.5 months), while in the control arm the median was 22 months (IQR 7 months to 46 months). Seven (6.9%) participants in the SMS arm were on second-line ART regimens, compared to 11 (11.1%) in the control arm. Initial retention in the trial for both arms at six months was 42% (participants who came for scheduled clinic visits), but increased to 82% after a phone call inviting participants to come for a final interview.

Outcome Adherence

At six months, there was no difference in the number of participants achieving >95% adherence, measuring by visual analogue scale (VAS) (risk ratio [RR] 1.06, 95% confidence interval [CI] 0.89 to 1.29, p=0.542). Similarly, there was no effect when measured by self-report of no missed doses (RR 1.01, 95% CI 0.87 to 1.16, p>0.999). The mean number of pharmacy refills was also not different between groups (mean difference [MD] 0.1, 95% CI -0.23 to 0.43; p=0.617). On sensitivity analysis, however, more participants in the SMS group achieved adherence of >90% at 6 months (RR 1.14, 95% CI 1.01 to 1.29, p=0.027).

Investigators performed regression analyses to determine the impact of baseline covariates on the primary outcomes. Higher levels of education (odds ratio [OR] 5.32, 95% CI 2.51 to 11.30; p>0.001) and being on a second-line regimen (OR 11.06, 95% CI 3.75 to 32.65, p<0.001) were statistically significant predictors of >95% adherence.

Secondary outcomes: dichotomous

At six months, there was no significant difference between the groups for any of the secondary dichotomous outcomes. Three participants died in the SMS group; one died in the control group (RR 2.94, 95% CI 0.31 to 27.79, p=0.322). The RR for the presence of a new OI was 1.15, 95% CI 0.64 to 2.07, p=0.632. Retention in the trial was equal between the groups (RR 0.95, 95% CI 0.83 to 1.08, p=0.399). With regard to adverse events, one woman in the intervention arm requested to withdraw from the study because she felt it had compromised her undisclosed HIV serostatus.

Secondary outcomes: continuous

There were insufficient data to appropriately calculate a mean difference in CD4 cell count (participants were n=34 for intervention, n=26 for control; MD -24.4 cells/µL, 95% CI: -101.3 cells/µL to 52.6 cells/µL, p=0.599) nor could a difference in viral load be calculated (n=0). There was no statistically significant difference in mean weight in kilograms (kg) (MD 1.60 kg, 95% CI -1.72 kg to 4.92 kg, p=0.344), nor for mean BMI (MD 0.81, 95% CI -0.32 to 1.94, p=0.159). Using the SF-12 QOL scale, there was no difference in quality of life between the groups (MD 0.04, 95% CI -0.12 to 0.20, p=0.629. Moderate levels of satisfaction were reported by participants who received text messages (65% reported that the messages were good, very good or excellent).


The authors conclude that motivational text messages did not significantly improve the rate of >95% adherence to ART among treatment-experienced patients in Cameroon after six months, though there was an improvement in the number of patients maintaining >90% adherence. The authors suggest that the six-month duration of their trial may not have been sufficiently long to detect an effect. They point out that confidentiality and disclosure are important considerations for the scale-up of text messaging interventions.

Risk of Bias

The risk of bias in this trial is low. Randomization, allocation and blinding procedures were appropriate. The report of the trial compares favorably to its protocol. There is no evidence of publication bias. Results should be interpreted somewhat cautiously, however, as adherence behavior was self-reported and may have been over-estimated. Even so, pharmacy refill data corresponded adequately to participant self-reports. Additionally, outcomes were assessed at six months, rather than at 12 months as had been done in other trials. This follow-up time may have been too short to find differences between the two groups.

In Context

This trial was unique in that it is the first to report an SMS intervention for ART adherence among treatment-experienced patients in Africa. Two recent trials of SMS interventions in Kenya convincingly demonstrated improved ART adherence at 12 months among patients recently initiating ART, who received weekly text messages.(1, 2) Duration on ART has been shown to have a negative effect on adherence in Cameroon,(3) and as the authors suggest, text-messaging interventions for ART adherence may be more efficacious in treatment-naïve populations. Additional trials in ART-experienced patients in Botswana(4) and Peru(5) are expected to be published in the coming year, and these findings will provide more insight into the efficacy of the intervention in this population.

Programmatic Implications

There is insufficient evidence at present to recommend this intervention for ART-experienced patients. In patients initiating ART, consistent with the positive findings of the Kenyan trials (1,2) and a Cochrane review of the evidence,(6) clinics should consider implementing mobile phone text messaging to promote adherence. Further research will show whether this intervention should be begun in treatment-experienced patients.


  1. Lester RT, Ritvo P, Mills EJ, Kariri A, Karanja S, et al (2010) Effects of a mobile phone short message service on antiretroviral treatment adherence in Kenya (WelTel Kenya1): a randomised trial. Lancet 376: 1838-1845.
  2. Pop-Eleches C, Thirumurthy H, Habyarimana JP, Zivin JG, Goldstein MP, et al (2011) Mobile phone technologies improve adherence to antiretroviral treatment in a resource-limited setting: a randomized controlled trial of text message reminders. AIDS 25: 825-834.
  3. Roux P, Kouanfack C, Cohen J, Marcellin F, Boyer S, et al. (2011) Adherence to antiretroviral treatment in HIV-positive patients in the Cameroon context: promoting the use of medication reminder methods. J Acquir Immune Defic Syndr 57 Suppl 1: S40-43.
  4. Botswana-UPenn Partnership. Steenhoff A et al. "Pilot Study of Text Message Reminders to Improve HIV Medication Adherence in Botswana." # NCT01001741
  5. Cell-POS." Curioso W and colleagues at Universidad Peruana Cayetano Heredia. "Evaluation of a Computer-Based System Using Cell Phones for HIV-Infected People in Peru." # NCT01118767
  6. Horvath T, Azman H, Kennedy GE, Rutherford GW (2012) Mobile phone text messaging for promoting adherence to antiretroviral therapy in patients with HIV infection. Cochrane Database Syst Rev 3 CD009756.